1. Field of the Invention
The present invention relates to an all-terrain vehicle. More particularly, the invention is a driving belt cooling structure for engines.
2. Description of the Related Art
Offroad vehicles or “ATVs” as they are commonly referred to are designed to be operated over rugged terrain. These vehicles are often operated on steep inclines and declines, on rough roads, and in mud and water.
These vehicles include a frame supported by wheels. In one common arrangement, the vehicle has four wheels. An internal combustion engine is used to power at least one, and most commonly all, of the wheels.
In this arrangement, a first drive shaft extends to a front axle and a second drive shaft extends to a rear axle. Each of these drive shafts extends generally parallel to a centerline of the vehicle extending in the front and rear directions.
The first and second drive shafts are driven by a crankshaft of the engine. The vehicle includes a transmission through which the first and second drive shafts are powered by the crankshaft.
It is desirable for the engine and related drive train of the vehicle to have a compact arrangement. To facilitate this goal, the engine is often arranged so that the crankshaft extends transverse to the longitudinal centerline of the vehicle. In this arrangement, the center of gravity of the engine is near the centerline of the vehicle, and the periphery of the engine does not extend far from this centerline.
On the other hand, this arrangement has the drawback that the rotation of the crankshaft must be transmitted to the first and second drive shafts which are arranged transverse to the crankshaft. This requires a transmission. To keep the transmission compact, one or more of the various shafts thereof may be supported in cantilevered fashion, which may reduce the useful life of the shafts. Additionally, in a variable speed transmission, heat due to friction within the transmission may reduce the useful life of various components of the transmission, such as the drive belt, for example.